Baron Baron is a rank of nobility or title of honour, often hereditary, in various European countries, either current or historical. The female equivalent is baroness. Typically, the title denotes an aristocrat who ranks higher than a lord or knig ...

Charles Cagniard de la Tour (31 March 1777 – 5 July 1859) was a French

engineer Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the l ...

and

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

. Charles Cagniard was born in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

, and after attending the

École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

became one of the ''ingénieurs géographiques''. He examined the mechanism of voice-production, invented a blowing machine and contributed to

acoustics Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician ...

by inventing an improved siren. He also studied yeast. In 1822, he discovered the critical point of a substance in his gun barrel experiments. Listening to discontinuities in the sound of a rolling flint ball in a sealed gun barrel filled with fluids at various temperatures, he observed the critical temperature. Above this temperature, the densities of the liquid and gas phases become equal and the distinction between them disappears, resulting in a single

supercritical fluid A supercritical fluid (SCF) is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous so ...

phase Phase or phases may refer to: Science *State of matter, or phase, one of the distinct forms in which matter can exist *Phase (matter), a region of space throughout which all physical properties are essentially uniform * Phase space, a mathematic ...

. He was made a baron in 1818, and died in Paris. Despite several claims to the contrary, no portraits of Baron Cagniard de la Tour exist.

Research

He was the author of numerous inventions, including the ''cagniardelle'', a blowing machine, which consists essentially of an

Archimedean screw The Archimedes screw, also known as the Archimedean screw, hydrodynamic screw, water screw or Egyptian screw, is one of the earliest hydraulic machines. Using Archimedes screws as water pumps (Archimedes screw pump (ASP) or screw pump) dates back ...

set obliquely in a tank of water in such a way that its lower end is completely and its upper end partially immersed, and operated by being rotated in the opposite direction to that required for raising water. He invented the improved

siren Siren or sirens may refer to: Common meanings * Siren (alarm), a loud acoustic alarm used to alert people to emergencies * Siren (mythology), an enchanting but dangerous monster in Greek mythology Places * Siren (town), Wisconsin * Siren, Wisc ...

,Charles Cagniard de la Tour (1819
"Sur la Sirène, nouvelle machine d'acoustique destinée à mésures les vibrations de l'air qui contient la son"
(On the siren, new acoustic machine to be used for measuring the vibrations of sound in air) ''Annales de chimie et de physique'', vol. 12, pages 167-171. which was named after him, around 1819 and he used it for ascertaining the number of vibrations corresponding to a sound of any particular pitch. He also made experiments on the mechanism of voice-production. In course of an investigation in 1822–1823 on the effects of heat and pressure on certain liquids he found that for each there was a certain temperature above which it refused to remain liquid but passed into the gaseous state, no matter what the amount of pressure to which it was subjected, and in the case of water he determined this critical temperature, with a remarkable approach to accuracy, to be 362 °C. He also studied the nature of

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

and the influence of extreme cold upon its life.

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Attribution: *

Research

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Further reading